When sudden voltage changes appear on the output terminal of a power amplifier, the power amplifier will be over-excited and give rise to a maximum output current and power loss until all compensating capacitors in the power amplifier have been recharged to the new voltage appearing on the output terminal. This can lead to the destruction of the power amplifier.
Current limitation in power amplifiers is effected in a manner known per se in that a resistor is interconnected in series with the power transistors in the amplifiers. When the current in such a resistor becomes high enough, a transistor is caused to conduct so that the driving current is shunted past the power transistor. The problem with these series resistors is that they, also during normal conditions, require extra overhead voltage which is not always readily available.